Hola amigos,

I've got a nasty problem. My computer sometimes simply shuts down and reboots. It happens while LFS'ing and gaming in general, but some times, in rare cases, just while doing office work or opening folders. It began when I accidently cut of the cooling air of my computer. I opened it up and kept it free of dust from that time on. In the past weeks the shut down rate increased, especially when gaming.

Microsoft Windows XP Home (SP3)
Graphic: nVidia GeForce 7650 GS (256 MB)
Processor: Intel Pentium 4 CPU 3,40GHz
1536MB RAM
Manufactor: MEDION

Important: The auto-reboot-function of XP is inactive, but it still shows no blue screen nither any other form of an error message.

It would be great if someone has a clue or an idea how to help me with it.

Thanks
Falke

Probably PSU on it's way out...or it could be overheating. or RAM.

It may also not give a blue screen for the above errors.

Download speedfan. Check that all of the internal fans (specifically the CPU fan) is free from dust and that there is no dust buildup in the heatsink which basically would act like a blanket. Even though you may clean your case many people don't bother checking inbetween the fins on the heatsink..

Since it happens under load from your description, it's worth downloading memtest86 and leaving that on overnight. If it crashes or bluescreens then chances are it's the RAM.

I'll go ahead and guess that your problem is caused by overheating. Remove the heatsink, give it a good clean, apply some new thermal grease on the CPU (remove the old) and put the heatsink back. I believe this will get you sorted.

Thanks S14 DRIFT and MadCatX for the quick help. I'm currently working through your advises, and I've seen the first results:
Using speedfan shows me that two sensors are experiencing a too high temperature under load. (according to speedfan, I think it is right with 75+ °C, even up to 80°C) and also that one sensor is broken (I don't have -56°C in my room, I'm sure)

Yeah that is too high. Make sure the fans are OK and there's no build up of dust as I mentioned. If everything looks OK, then I'd recommendy following MadCat's instructions. If you are in any way not sure of what to do, either spend a good hour reading a guide (I'm too lazy to find one) or take it to a qualified computer technician.

My Q6600 doesn't get that hot and there's a nuclear reactor for a graphics card (in terms of heat not performance) about 1 inch from it. Also I haven't cleaned the case for over a year. :> Problem?

I need to look for the dust tomorrow actually, as daylight is gone and my bulb decided to never get switched on again. But hey, at least know how to change that
A friend of mine suggested me to look out for some virus. He told me there were some similar problems with a virus infection due to a loophole in XP SP3.

Quote from TFalke55 :

A friend of mine suggested me to look out for some virus. He told me there were some similar problems with a virus infection due to a loophole in XP SP3.

what would be the point of randomly turning off someone's computer though, that makes no sense... it would be more advantageous for them to keep it on and use it for nefarious purposes.

Quote from bunder9999 :

what would be the point of randomly turning off someone's computer though, that makes no sense... it would be more advantageous for them to keep it on and use it for nefarious purposes.

I don't know, I'm not really in that matter and I have only a limited clue about soft- & hardware in general

I did consider a virus at first but these tend to be genuinely random. The OP's issues are seemingly linked with computer usage and stress.

If you think about it, not all viruses are out for financial benefit or some sort of botnet for use in random hackings. Sometimes people just like pissing other people off.

Also, you could check the disk out with MHDD. It wouldn't be the first time for me to see that kind of behavior because of the hard drive.
And open up the box and check the capacitors if they're inflated. A small bulge is visible on top of them if they're inflated. Inflated = bad. Then you've got your MB to replace.

It really seems to be dust related. The temperature is now 10°C lower then prior to the clean up and is stabil. Even under load. I'll keep an eye on it, maybe just one of murphy's laws are the reason for this stability.

Thanks for all the help

has your local weather improved over the past weeks? ambient temperature goes up in string/summer.

Quote from dadge :

has your local weather improved over the past weeks? ambient temperature goes up in string/summer.

I've a pretty constant indoor temperature between 21°C at cold nights and 22°C at sunny days. that's not the problem

if heat is the problem, you have to make sure you have covered all the possible causes. i tend to clean (dust) my pc more during the summer just because it the air can get sticky when it's warmer.
but yeah, dust is a bitch. it might be an idea to invest in some dust filters for your fans.

Before buying filters, try to pick the machine of the floor, specially if it sits on a carpet. Don't have to be on the ceilling, just a height of a shoe box should improve the dust issue. I'd do that anyway, filters or no filters.